Labour will oppose proposals for a South West pay "cartel" in the NHS "to the hilt", Shadow Heath Secretary Andy Burnham has told conference.
Some 20 NHS boards in the region have established the South West Pay Consortium, which includes hospitals in Taunton, Plymouth and Exeter.
Set up to explore ways of meeting unprecedented financial challenges, unions fear by ending uniform national pay deals it will drive down wages and conditions.
Mr Burnham attacked new Health Secretary Jeremy Hunt for failing to make his views public on the plans, which have yet to be agreed.
He told delegates: "It's hard to be a Shadow when you're up against the Invisible Man.
"Hunt Jeremy – the search is on for the missing Health Secretary. A month in the job but not a word about thousands of nursing jobs lost. Not one word about crude rationing, older people left without essential treatment. Not a word about moves in the South West to break national pay.
"Jeremy Hunt might be happy hiding behind trees while the front-line of the NHS takes a battering. But, conference, for as long as I do this job, I will support front-line staff and defend national pay in the NHS to the hilt."
Mr Hunt's predecessor, Andrew Lansley, was among the keenest proponents of local pay for state workers, which is being considered across the public sector by an independent body.
Health trusts in the region have said the consortium has been established in response to the "serious financial and operational challenges" facing the NHS.
The Government is looking to reform its Agenda for Change programme – which sets pay bands across the country for NHS staff excluding doctors, dentists and some senior managers – so that it includes more "flexibility" to set pay and conditions to reflect the local market.
At a fringe meeting on the eve of his keynote speech to Manchester conference, Mr Burnham said regional pay in the NHS would lead to hospitals poaching staff from one another and drive costs up in the long run.
If there were to be regional pay, it is less wealthy areas like Liverpool, Manchester, Newcastle and Sheffield – rather than richer areas in the South East – where staff should be paid more, as they face the toughest health challenges, he said. Devon and Cornwall are among the poorest counties in the country.
He went on that the Government's NHS reforms were creating a "fragmented" health system. Mr Burnham admitted Labour had made some mistakes in its handling of health, but had left a "successful, self-confident NHS with the lowest ever waiting lists and the highest patient satisfaction".